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This steak sandwich is my favorite quick indulgence when I want something hearty and packed with flavor but without the fuss of a full meal. It brings together tender, seasoned steak with rich herb butter, sweet caramelized onions, and melty Havarti cheese all in a crunchy baguette. Perfect for lunch or a casual dinner, it feels like a special treat made with everyday ingredients.
I first threw this together after a busy workday and it instantly became a go-to for satisfying hunger without making a mess in the kitchen.
Ingredients
- Softened unsalted butter: gives you a creamy base for the herb spread
- Fresh dill: adds a bright, slightly tangy note that cuts through the richness—choose fresh and vibrant sprigs for the best taste
- Garlic cloves: give a punch of savory depth—crush or finely mince to infuse the butter fully
- Steak: provides the meaty star element—opt for a tender cut like ribeye or sirloin and chill it slightly before slicing for cleaner cuts
- Oil for searing: ensures a good crust on the steak—use a high smoke point oil like canola or vegetable
- Salt: seasons the steak perfectly—use coarse sea salt for better control
- Yellow onion: caramelizes beautifully with natural sweetness, enhancing the sandwich layers
- Havarti cheese: melts easily and has a buttery, mild flavor—pick thin slices for even melting
- Baguette: holds the fillings well and adds a crunchy texture—look for a fresh baguette with a crisp crust
Instructions
- Build The Herb Butter Spread:
- Combine softened butter with crushed garlic and diced fresh dill in a bowl. Stir until evenly mixed, creating a smooth and flavorful spread that will add moisture and brightness to the sandwich. Set this aside while preparing the rest.
- Prep The Steak:
- Place your steak in the freezer for 10 to 15 minutes to firm it up for easier slicing. Then cut into thin, uniform strips. This step helps the steak cook quickly and results in tender bites.
- Sear The Steak:
- Heat a tablespoon of oil in a skillet over high heat until shimmering. Add the steak strips and season with salt. Let the steak cook undisturbed for about two to three minutes until seared on one side and golden. Flip and cook for another two minutes. Remove the steak from the pan and keep warm.
- Caramelize The Onions:
- Using the same skillet, add sliced half-rings of yellow onion. Reduce heat to medium and sauté, stirring occasionally for about ten minutes until the onions turn a deep golden brown and develop sweetness. Remove from the heat and set aside.
- Assemble The Sandwich:
- Slice the baguette lengthwise. Spread both cut sides generously with the herb butter mix. Layer the steak, then the caramelized onions on one half of the bread. Top with slices of Havarti cheese before closing the sandwich.
I love the herb butter because it brightens the richness of the steak and cheese. It reminds me of weekend lunches my family made where everyone customized their sandwich and lingered talking while tearing into these messy, delicious bites.
Storage tips
Keep leftover sandwich components separate if possible to maintain freshness. Store steak and onions in an airtight container up to three days in the fridge. Herb butter keeps well covered in the fridge for about a week.
Ingredient swaps
Swap Havarti cheese for provolone or fontina for a milder melt or sharp cheddar if you like bold flavors. Use fresh parsley or tarragon in place of dill for a different herb twist. Choose a ciabatta roll or kaiser bun if you want a softer bread.
Serving ideas
Serve this sandwich with a simple green salad dressed with lemon for balance. Pickles or a tangy slaw on the side bring nice crunch and acidity. A handful of kettle-cooked chips makes for a satisfying crunchy companion.
This steak sandwich is a tasty, quick treat well worth the little effort of preparation.
Frequently Asked Recipe Questions
- → How can I slice the steak thinly?
Partially freezing the steak for about 15 minutes firms it up, making thin, even slices easier to achieve.
- → What is the best way to cook the steak for this dish?
Heat a skillet with oil over high heat and cook the steak strips just until golden brown for a tender texture and rich flavor.
- → How should I prepare the onions?
Slice the onions into half rings and sauté them in the same skillet until they turn golden and caramelized, adding sweetness and depth.
- → Can I substitute Havarti cheese with another type?
Yes, milder cheeses like mozzarella or provolone can be used, but Havarti's creaminess complements the steak and herbs well.
- → What is the herb butter made of?
The herb butter combines softened unsalted butter with fresh dill and crushed garlic for a bright, flavorful spread.
- → How do I assemble the sandwich for best results?
Spread the herb butter on both baguette halves, then layer the steak slices, sautéed onions, and cheese, allowing the warmth to slightly melt the cheese.